It is often necessary to lay a pipe or rod beneath existing highways or structures. The present invention allows conduits to be laid without tearing up the highway surface or interfering with the existing structure by avoiding the necessity of having to dig a trench for laying the pipe or rod in the ground. Rather, the present invention pushes or pulls a rod or pipe through the earth underneath the highway or structure.
Oftentimes the location where pipes or rods are to be placed in the ground is not very accessible. It is therefore desirable to have a portable rod and pipe pulling and pushing apparatus which will perform the above-described function and yet allow access to hard-to-get-at locations.
Several patents have issued on apparatus which perform the above-described function, examples of which are U.S. Pat. No. 3,227,419 (Lackey), U.S. Pat. No. 3,726,506 (Vanderwaal et al.), U.S. Pat. No. 3,834,668 (Casey), and U.S. Pat. No. 4,000,879 (Martin et al.). The apparatus of the prior art all have a frame with an assembly of sorts movable along the frame by various means. In addition, the previously mentioned prior art have various types of gripping mechanisms for gripping the rod or pipe which is being pulled or pushed, some of the embodiments revealing reversible mechanisms so that the apparatus from one position may either pull or push a rod or pipe.
Many of these devices have functioned adequately. The devices, however, must be operated carefully. Furthermore, the gripping mechanisms must be monitored frequently for unacceptable wear conditions. The present invention alleviates several operational and maintenance weaknesses of the known devices.